Novel bio-conjugate materials: soybean peroxidase immobilized on bioactiveglasses containing Au nanoparticles

In the field of implantation, the delivery and/or immobilization of biomolecules developing a specificaction on bone mineralization has attracted great attention in the last few years. In fact, a widespectrum of enzymes and proteins have been grafted with different methods onto/within implantedmaterials. Bioactive glasses and glass-ceramics, due to their tailorable properties in terms of chemicalcomposition, reactivity, and easiness of manufacturing, represent good scaffolds for enzymeimmobilization. These biomaterials are well known for their peculiar surface reactivity promoting,when contacted with real or simulated body fluids, the formation of an hydroxy-carbonate apatitelayer. The aim of the present contribution has been to immobilize, via a covalent linkage, an enzyme onthe glass surface through the formation of self-assembled monolayers (SAMs), in order to obtaina stable bio-conjugate useful as a material bio-implantable into the human body. The innovation of thisstudy resides in the use of a new method of protein immobilization on the glass surface. Unlike otherworks, in which a preliminary silanization process has often been used, the introduction of goldnanoparticles (AuNPs) in the glass composition allowed us to exploit the easy SAMs formation processon the AuNPs dispersed in the bioactive glass matrix and, consequently, to immobilize an enzyme(soybean peroxidase, SBP, in the present case) on the SAMs. A thorough characterization of thematerials, at different steps of the functionalization process, has been also reported, together with invitro activity tests of immobilized SBP, compared with merely adsorbed SBP, and cytotoxicity testsusing human osteoblast (MG-63) cells. Overall, a new bio-conjugate material, able to maintain itsactivity over time and to decrease the oxidative stress when in contact with MG-63 cells, has beenobtained.